Genetic Structure of Two Protist Species (Myxogastria, Amoebozoa) Suggests Asexual Reproduction in Sexual Amoebae

Abstract

Plasmodial slime molds (Myxogastria or Myxomycetes) are common and widespread unicellular organisms that are commonly assumed to have a sexual life cycle culminating with the formation of often macroscopic fruiting bodies that efficiently disseminate spores. However, laboratory studies based on mating compatibility revealed the coexistence of asexual as well as sexual strains. To test this hypothesis in natural populations, we investigated the genetic variability of two species of the genus Lamproderma. Detailed ecological relevés were carried out in 2007 and 2009 in several deep ravines in the Elbsandsteingebirge (Saxony, south-eastern Germany). Morphological characters of 93 specimens of Lamproderma were recorded and genetic analyses, based on the small subunit ribosomal gene, the internal transcribed spacer 1 and partial elongation factor 1α sequences were carried out for 52 specimens. Genetic analyses showed the existence of two major clades, each composed of several discrete lineages. Most of these lineages were composed of several identical sequences (SSU, ITS 1 and EF-1α) which is explained best by an asexual mode of reproduction. Detrended Correspondence Analysis of morphological characters revealed two morphospecies that corresponded to the two major clades, except for one genotype (Lc6), thus challenging the morphospecies concept. Genetic patterns were not related to the geographical distribution: specimens belonging to the same genotype were found in distinct ravines, suggesting effective long-distance dispersal via spores, except for the Lc6 genotype which was found only in one ravine. Implications for the morphological and biological species concept are discussed.

Using environmental niche models to test the ‘everything is everywhere’ hypothesis for Badhamia

“…Previous molecular studies on other myxomycete morphospecies did not show any clear relationship between genetic variants and the geographical origin of the specimens (Winsett and Stephenson 2008;Fiore-Donno et al, 2011). However, B. melanospora displays a clear geographic pattern.…”

Metacommunity analysis of amoeboid protists in grassland soils

“…Providing that specific molecular probes are used, dark-spore Myxomycetes can be recovered from soils 27 28 29 , litter 30 and air 31 . This class benefits from a well-studied phylogeny 32 33 34 35 , with a major division between the dark spore and bright spore clades, the former being the better studied to date and the group targeted here.…”

Genetic barcoding of dark‐spored myxomycetes (Amoebozoa)—Identification, evaluation and application of a sequence similarity threshold for species differentiation in NGS studies

“…Likewise, Fiore‐Donno et al. () found intraspecific differentiation within Lamproderma puncticulatum and L. columbinum using a larger fraction (659 bp) of the SSU gene combined with ITS sequences and EF1A markers. Similarly, intraspecific subclades were found for L. ovoideum (M. Borg Dahl et al., unpublished results), for the bright‐spored species Tubifera ferruginosa (Leontyev et al., ) and Hemitrichia serpula (Dagamac et al., ).…”

“…Empirical evidence of whether all morphospecies reflect true biospecies is lacking (reviewed in Clark & Haskins, ). Apart from division of amoebae, which should allow for clonal amoebal populations, asexual reproduction modes have been suggested (Clark & Haskins, ; Fiore‐Donno, Novozhilov, Meyer, & Schnittler, ; Walker & Stephenson, ). However, recent studies (Feng & Schnittler, ; Feng et al., ) concluded that sexual reproduction seems to dominate in natural populations.…”